1. Technical Field of the Invention
The present invention relates to a waveform data processing apparatus with a dedicated data bus suitably used for connection among musical sound processing devices.
2. Prior Art
A sound board mounted on an electronic musical instrument, personal computer or the like is equipped with a plurality of LSIs which processes musical sound signals, and these LSIs are connected by connection lines for transmitting and receiving the musical sound signals, thereby enabling necessary functions. Here, an example of the sound board mounted on the electronic musical instrument is shown in FIG. 1(a). In the drawing, 100 denotes a sound board, on which sound generator LSIs 102, 104 are mounted. The sound generator LSIs 102, 104 comprise, for example, waveform synthesizing sections which generate musical sound signals of a plurality of channels, and mixers which mix the musical sound signals of a plurality of channels as necessary. Further, 106, 108 denote DSPs (digital signal processors), which apply various kinds of effect processing to the generated musical sound signals.
The musical sound signals which have been applied the effect processing are again supplied to the sound generator LSIs 102, 104. In addition, the sound generator LSIs 102, 104 also exchange musical sound signals between them. Then, the musical sound signals to be finally output are supplied from the sound generator LSI 104 to a DA converter 110 where they are converted into analog signals. 114 denotes a plug-in board which can be added optionally and is equipped with an additional waveform synthesizing section, DSP or the like. This plug-in board 114 is plugged into a connector 112 as necessary.
Furthermore, another configuration of the sound board is shown in FIG. 1(b). In the drawing, 120 denotes another sound board, and sound generator LSIs 122, 124 inside therein each synthesize musical sound signals of a plurality of channels. The synthesized musical sound signals are mixed by mixers in the sound generator LSIs 122, 124, and the musical sound signals, which result from the mixing, are supplied to DSPs 126, 128. The DSPs 126, 128 apply effect processing to the supplied musical sound signals. Here, the musical sound signals to which the effect processing is applied by the DSP 126 are supplied to the DSP 128. When a plug-in board 134 is plugged into a connector 132, musical sound signals generated by this plug-in board 134 are also supplied to the DSP 128. These digital signals are further mixed in the DSP 128, and results of the mixing are converted to analog signals by a DA converter 130.
In the examples of FIGS. 1(a) and 1(b), even if the sound generator LSIs and DSPs used in the sound boards 100, 120 are completely common parts, they are connected in different states, so that the sound boards 100, 120 themselves are not compatible. In other words, hardware components must be designed and produced for each kind of sound board, depending on the function that the sound board is designed to carry out.
On the other hand, a technique is known in which a hardware common connection state is shared by a plurality of nodes, while a exchanging state of signals is set depending on the function that will finally be needed, thereby setting a logical connection relationship. For example, the applicant has proposed a network standard called mLAN (trademark) wherein an electronic musical instrument or equipment such as a synthesizer or digital mixer, and a computer or the like are connected by serial cables on an IEEE1394 interface, thereby exchanging musical sound signals or music performance information.
In addition, Japanese Patent Publication Laid-open No. 5-188967 discloses a technique in which an AD converter, hard disk and a waveform memory are connected on a common bus, and waveform data or the like is exchanged among these nodes on a time-divisional basis.
As described above, in the examples of FIGS. 1(a) and 1(b), hardware components must be designed and produced for each kind of sound board because the sound boards 100, 120 are not compatible, thus increasing designing costs and making it difficult to lower costs by mass production. Therefore, it is preferable, for example, that sound generator LSIs 142, 144, DSPs 146, 148, a DA converter 150 and a plug-in board 154 (via a connector 152) can be connected on a common bus 156, as shown in FIG. 1(c). That is, if the physical hardware connection relationship is common while logical connection relation can be set as required at the same time, the sound board in FIG. 1(c) can carry out functions equivalent to the sound boards shown in FIG. 1(a) or 1(b), for example.
In this case, it is important that a suitable kind of standard is employed to connect the LSIs to the bus 156. The mLAN™ mentioned above is based on the assumption that independent equipment such as the synthesizer or digital mixer is to be the node, so that signal compositions are complicated and it is impracticable to adapt individual LSIs to the mLAN standards. Moreover, the technique disclosed in Japanese Patent Publication Laid-open No. 5-188967 allows the specific nodes that are shown in this publication to exchange waveform data or the like, but can not be adapted to various kinds of nodes in a general and multi-purpose manner.